CN113972475B

CN113972475B - Antenna structure

Info

Publication number: CN113972475B
Application number: CN202010723214.7A
Authority: CN
Inventors: 黄钧麟
Original assignee: Wistron Neweb Corp
Current assignee: Wistron Neweb Corp
Priority date: 2020-07-24
Filing date: 2020-07-24
Publication date: 2024-03-08
Anticipated expiration: 2040-07-24
Also published as: CN113972475A

Abstract

An antenna structure. The antenna structure includes: a circulating radiation part, a balance radiation part, a first additional radiation part and a second additional radiation part; the circulating radiation part is provided with a first feed-in point; the balance radiation part is provided with a second feed-in point and is at least coupled to a first connecting point on the circulation radiation part, wherein the balance radiation part is substantially surrounded by the circulation radiation part; the first additional radiation part is coupled to a second connection point on the circulating radiation part; the second additional radiation part is coupled to a third connection point on the circulating radiation part; the circulating radiation portion is disposed between the first additional radiation portion and the second additional radiation portion. The antenna structure of the invention has at least the advantages of isotropy, small size, wide frequency band, planarization design and the like, so the antenna structure is very suitable for being applied to various communication devices.

Description

Antenna structure

Technical Field

The present invention relates to an antenna structure (Antenna Structure), and more particularly to an antenna structure that is nearly Isotropic.

Background

With the development of mobile communication technology, mobile devices are becoming increasingly popular in recent years, and common examples are: portable computers, mobile phones, multimedia players, and other portable electronic devices with hybrid functions. To meet the needs of people, mobile devices often have wireless communication capabilities. Some cover long range wireless communication ranges, such as: mobile phones use 2G, 3G, LTE (Long Term Evolution) systems and the frequency bands of 700MHz, 850MHz, 900MHz, 1800MHz, 1900MHz, 2100MHz, 2300MHz, and 2500MHz for communication, and some cover short range wireless communication ranges such as: wi-Fi, bluetooth systems use the frequency bands of 2.4GHz, 5.2GHz, and 5.8GHz for communication.

The wireless network base station (Wireless Access Point) is an essential element for enabling mobile devices to access the internet at high speed in the room. However, since the indoor environment is full of signal reflection and Multipath Fading (Multipath Fading), the wireless network base station must be able to process signals from all directions simultaneously. Therefore, how to design a nearly Isotropic antenna in the limited space of the wireless network base station has become a challenge for designers today.

Accordingly, there is a need to provide an antenna structure that meets the above-mentioned needs.

Disclosure of Invention

In a preferred embodiment, the present invention provides an antenna structure, comprising: a circulating radiation part with a first feed point; a balance radiation part having a second feed point and coupled to at least a first connection point on the circulation radiation part, wherein the balance radiation part is substantially surrounded by the circulation radiation part; a first additional radiating portion coupled to a second connection point on the circulating radiating portion; and a second additional radiating portion coupled to a third connection point on the circulating radiating portion; wherein the circulating radiation portion is disposed between the first additional radiation portion and the second additional radiation portion.

In some embodiments, the antenna structure is capable of producing a radiation pattern that is approximately isotropic.

In some embodiments, the antenna structure further comprises: the medium substrate is provided with the circulating radiation part, the balance radiation part, the first additional radiation part and the second additional radiation part.

In some embodiments, the antenna structure covers an operating frequency band between 2400MHz and 2500 MHz.

In some embodiments, the circulating radiation portion presents a hollow rectangle.

In some embodiments, the circulating radiation portion has a first end and a second end, and the first feeding point is located at the first end of the circulating radiation portion.

In some embodiments, the length of the circulating radiation portion is between 0.45 times and 0.85 times the wavelength of the operating band.

In some embodiments, a hollow portion of the circulating radiation portion has an aspect ratio between 0.66 and 1.66.

In some embodiments, the circulating radiation portion further includes a first coupling portion and a second coupling portion, and a coupling gap is formed between the first coupling portion and the second coupling portion.

In some embodiments, the balanced radiating portion exhibits a U-shape.

In some embodiments, the balanced radiating portion includes a first branch portion, a second branch portion, and a connecting portion, and a slot is formed between the first branch portion and the second branch portion.

In some embodiments, the first branch portion of the balanced radiating portion is further coupled to the second end of the circulating radiating portion, and the second feed point is located at the second branch portion of the balanced radiating portion.

In some embodiments, the length of the balanced radiating portion is between 0.05 times and 0.45 times the wavelength of the operating band.

In some embodiments, the first additional radiating portion exhibits an L-shape.

In some embodiments, the length of the first additional radiating portion is between 0.11 and 0.31 wavelengths of the operating band.

In some embodiments, the first additional radiating portion further comprises a first end bend portion.

In some embodiments, the second additional radiating portion exhibits an inverted L-shape.

In some embodiments, the length of the second additional radiating portion is between 0.11 and 0.31 wavelengths of the operating band.

In some embodiments, the second additional radiating portion further comprises a second end bend portion.

In some embodiments, the first and second additional radiating portions extend in substantially the same or mutually adjacent directions.

Compared with the prior art, the antenna structure of the invention has the advantages of at least isotropy, small size, wide frequency band, planarization design and the like, so the antenna structure is very suitable for being applied to various communication devices.

Drawings

Fig. 1 shows a schematic diagram of an antenna structure according to an embodiment of the invention.

Fig. 2A shows a radiation pattern diagram of an antenna structure according to an embodiment of the invention.

Fig. 2B shows a radiation pattern diagram of an antenna structure according to an embodiment of the invention.

Fig. 2C shows a radiation pattern diagram of an antenna structure according to an embodiment of the invention.

Fig. 3 shows a schematic diagram of an antenna structure according to an embodiment of the invention.

Fig. 4 shows a schematic diagram of an antenna structure according to an embodiment of the invention.

Fig. 5 shows a schematic diagram of an antenna structure according to an embodiment of the invention.

Fig. 6 shows a schematic diagram of an antenna structure according to an embodiment of the invention.

Fig. 7 shows a schematic diagram of an antenna structure according to an embodiment of the invention.

Fig. 8 shows a schematic diagram of an antenna structure according to an embodiment of the invention.

Description of main reference numerals:

100. 300, 400, 500, 600, 700, 800 antenna structure

110. 310, 410, 510 circulating radiation section

111. 311 first end of the circulating radiation portion

112. 312 second end of the circulating radiation portion

118. Hollow part of circulation radiation part

120. 320, 420 balance radiation portion

121. First end of balance radiation part

122. Second end of balance radiation part

124. 324 balance the first branch portion of the radiating portion

125. 325 second branch portion of balanced radiation section

126. 326 balance the connection portion of the radiating portion

128. Slotted hole

130. 330, 430 first additional radiation part

131. 331 first end of the first additional radiating portion

132. 332 second end of the first additional radiating portion

140. 340, 440 second additional radiation part

141. 341 a first end of a second additional radiation portion

142. 342 second end of the second additional radiating portion

180. Dielectric substrate

190. Signal source

319. End widening portion of circulation radiating portion

334. The first end bending part of the first additional radiation part

344. The second end bending part of the second additional radiation part

414. 514 first coupling portion of the circulating radiation section

415. Second coupling portion of 515-cycle radiating portion

CP1 first connection point

CP2 second connection point

CP3 third connection point

D1 First distance of

D2 Second distance

D3 First distance of

FP1 first feed-in point

FP2 second feed point

GC1 coupling gap

L, L1 length of L2, L3 and L4

W width

X X shaft

Y Y shaft

Z Z shaft

Detailed Description

The following detailed description of the invention refers to the accompanying drawings, which illustrate specific embodiments of the invention.

Certain terms are used throughout the description and claims to refer to particular components. Those of ordinary skill in the art will appreciate that a hardware manufacturer may refer to the same element by different names. The description and claims do not take the form of an element differentiated by name, but rather by functional differences. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. The term "substantially" means that within an acceptable error range, a person skilled in the art can solve the technical problem within a certain error range, and achieve the basic technical effect. In addition, the term "coupled" as used herein includes any direct or indirect electrical connection. Accordingly, if a first device couples to a second device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections.

The following disclosure provides many different embodiments, or examples, for implementing different features of the disclosure. The following disclosure describes specific examples of various components and arrangements thereof to simplify the description. Of course, these specific examples are not intended to be limiting. For example, if the disclosure describes a first feature being formed on or over a second feature, that means that it may include embodiments in which the first feature is in direct contact with the second feature, and that additional features may be formed between the first feature and the second feature, such that the first feature and the second feature may not be in direct contact. In addition, the following disclosure of different examples may reuse the same reference symbols or (and) labels. These repetition are for the purpose of simplicity and clarity and do not in itself dictate a particular relationship between the various embodiments or (and) configurations discussed.

Fig. 1 shows a schematic diagram of an antenna structure (Antenna Structure) 100 according to an embodiment of the invention. The antenna structure 100 can be applied to a communication device, for example: a wireless network base station (Wireless Access Point). As shown in fig. 1, the antenna structure 100 includes at least: a circulating radiation portion (Loop Radiation Element) 110, a balancing radiation portion (Balance Radiation Element) 120, a first additional radiation portion (Additional Radiation Element) 130, and a second additional radiation portion 140. The circulating radiation portion 110, the balance radiation portion 120, the first additional radiation portion 130, and the second additional radiation portion 140 may be made of metal materials, for example: copper, silver, aluminum, iron, or alloys thereof.

In some embodiments, the antenna structure 100 further includes a dielectric substrate (Dielectric Substrate) 180. The circulating radiation portion 110, the balance radiation portion 120, the first additional radiation portion 130, and the second additional radiation portion 140 may collectively form a Planar Structure (Planar Structure) and be disposed on the same surface of the dielectric substrate 180. For example, the dielectric substrate 180 may be an FR4 (frame reflector 4) substrate, a printed circuit board (Printed Circuit Board, PCB), or a flexible circuit board (Flexible Circuit Board, FCB). However, the present invention is not limited thereto. In other embodiments, the circulating radiation portion 110, the balance radiation portion 120, the first additional radiation portion 130, and the second additional radiation portion 140 may be disposed on different surfaces (e.g., an upper surface and a lower surface opposite to each other) of the dielectric substrate 180, and coupled to each other by one or more conductive through devices (Conductive Via Element) without affecting the efficacy of the present invention.

The circulating radiation Portion 110 may generally have a Hollow rectangular shape, wherein a Hollow Portion 118 may be formed inside the circulating radiation Portion 110. In detail, the circulating radiation portion 110 has a first end 111 and a second end 112, wherein a first Feeding Point FP1 is located at the first end 111 of the circulating radiation portion 110. The first feed point FP1 may be coupled to the positive electrode (Positive Electrode) of a Signal Source 190. For example, the signal source 190 may be a Radio Frequency (RF) module that may be used to excite the antenna structure 100. In addition, the second end 112 and the first end 111 of the circulation radiating portion 110 are adjacent to each other. It should be noted that the term "adjacent" or "adjacent" in the present specification may refer to the corresponding elements having a distance smaller than a predetermined distance (e.g., 5mm or less), and may also include the case where the corresponding elements are in direct contact with each other (i.e., the distance is reduced to 0). In other embodiments, the circulating radiation portion 110 may be modified to have a different shape, for example: a hollow circle, a hollow triangle, a hollow trapezoid, or a hollow ellipse.

The balance radiating portion 120 may generally take on a U-shape, which may be generally surrounded by the circulation radiating portion 110. In detail, the balanced radiating portion 120 has a first end 121 and a second end 122 adjacent to each other, wherein a second feeding point FP2 is located at the second end 122 of the balanced radiating portion 120. The second feed point FP2 may be coupled to a negative electrode (negative electrode) of the signal source 190. In some embodiments, the balanced radiating Portion 120 includes a first Branch Portion (Branch) 124, a second Branch Portion 125, and a connection Portion (Connection Portion) 126, wherein the first Branch Portion 124 is adjacent to or includes the first end 121 of the balanced radiating Portion 120, the second Branch Portion 125 is adjacent to or includes the second end 122 of the balanced radiating Portion 120, and the connection Portion 126 is coupled between the first Branch Portion 124 and the second Branch Portion 125. The Connection portion 126 is coupled to a first Connection Point CP1 on the circulating radiation portion 110, which may be located approximately at the center of an edge of the circulating radiation portion 110. In some embodiments, the first branch portion 124 (or the first end 121 of the balance radiating portion 120) may also be coupled to the second end 112 of the circulation radiating portion 110. The first and second branch portions 124, 125 may each be straight and may be substantially parallel to each other. In addition, a slot 128 may be formed between the first leg portion 124 and the second leg portion 125. In some embodiments, the Slot 128 may be a monopolar Slot (monopolar Slot).

The first additional radiating portion 130 may substantially take on an L-shape. In detail, the first additional radiating portion 130 has a first End 131 and a second End 132, wherein the first End 131 of the first additional radiating portion 130 is coupled to a second connection point CP2 on the circulating radiating portion 110, and the second End 132 of the first additional radiating portion 130 is an Open End (Open End). In some embodiments, the second connection point CP2 is located at a corner of the circulating radiating portion 110.

The second additional radiating portion 140 may substantially take on an inverted L shape. In detail, the second additional radiating portion 140 has a first end 141 and a second end 142, wherein the first end 141 of the second additional radiating portion 140 is coupled to a third connection point CP3 on the circulating radiating portion 110, and the second end 142 of the second additional radiating portion 140 is an open end. The second end 142 of the second additional radiating portion 140 and the second end 132 of the first additional radiating portion 130 may extend in substantially the same direction. In some embodiments, the third connection point CP3 is located at the opposite corner of the circulating radiation portion 110, such that the second connection point CP2, the third connection point CP3, and the first end 111 and the second end 112 of the circulating radiation portion 110 may all be located substantially on the same line. However, the present invention is not limited thereto. In other embodiments, the first end 111 and the second end 112 of the circulating radiation portion 110 may not be aligned (or located on different lines) with each other. In addition, the circulating radiation portion 110 and the balance radiation portion 120 therein may be disposed between the first additional radiation portion 130 and the second additional radiation portion 140.

In some embodiments, the antenna structure 100 may cover an operating frequency band (Operation Frequency Band). For example, the operating frequency band may be between 2400MHz and 2500MHz, but is not limited thereto. Thus, the antenna structure 100 will support broadband operation of at least WLAN (Wireless Local Area Networks) 2.4 GHz.

Fig. 2A shows a radiation pattern diagram (Radiation Pattern) of the antenna structure 100, measured along the XZ plane, according to an embodiment of the present invention. Fig. 2B shows a radiation pattern diagram of the antenna structure 100 according to an embodiment of the invention, which is measured along the YZ plane. Fig. 2C shows a radiation pattern diagram of the antenna structure 100 according to an embodiment of the invention, which is measured along the XY plane. According to the measurement results of fig. 2A, 2B, and 2C, the antenna structure 100 may generate an approximately Isotropic (Isotropic) radiation pattern.

In some embodiments, the principle of operation of the antenna structure 100 may be as follows. When excited by the signal source 190, the circulating radiation portion 110 mainly provides Polarization and energy distribution in a vertical direction (e.g., parallel to the Y-axis direction), and the first and second additional radiation portions 130 and 140 mainly provide Polarization and energy distribution in a horizontal direction (e.g., parallel to the X-axis direction), so that the radiation pattern of the antenna structure 100 can be as close to ideal isotropy as possible. In addition, the addition of the balanced radiating portion 120 can make the current distribution on the antenna structure 100 more uniform, so as to overcome the problem of asymmetric design caused by the deviation of the first feed point FP1 and the second feed point FP2 to the same side of the antenna structure 100.

In some embodiments, the element dimensions of the antenna structure 100 may be as follows. The length L1 of the circulating radiation portion 110 (i.e., the length L1 from the first end 111, through the first connection point CP1, and then to the second end 112) may be between 0.45 times and 0.85 times the wavelength (0.45 λ and 0.85 λ), preferably about 0.65 times the wavelength (0.65 λ) of the operating band of the antenna structure 100. The length L2 of the balanced radiating portion 120 (i.e., the length L2 from the first end 121, through the connecting portion 126, and to the second end 122) may be between 0.05 times and 0.45 times the wavelength (0.05λ and 0.45λ), preferably about 0.25 times the wavelength (0.25λ) of the operating band of the antenna structure 100. The length L3 of the first additional radiating portion 130 (i.e., the length L3 from the first end 131 to the second end 132) may be between 0.11 times and 0.31 times the wavelength (0.11λ and 0.31λ), preferably about 0.21 times the wavelength (0.21λ) of the operating band of the antenna structure 100. The length L4 of the second additional radiating portion 140 (i.e., the length L4 from the first end 141 to the second end 142) may be between 0.11 times and 0.31 times the wavelength (0.11λ and 0.31λ), preferably about 0.21 times the wavelength (0.21λ) of the operating band of the antenna structure 100. The hollow portion 118 of the circulating radiation portion 110 has a length L and a width W, and an aspect ratio (i.e., L/W) thereof may be between 0.66 and 1.66, and preferably may be about 1.16. The second end 132 of the first additional radiating portion 130 and the second end 142 of the second additional radiating portion 140 have a first distance D1 therebetween, wherein a ratio of the length L3 of the first additional radiating portion 130 to the first distance D1 (i.e., L3/D1) may be between 0.6 and 1.6, preferably about 1.1, and a ratio of the length L4 of the second additional radiating portion 140 to the first distance D1 (i.e., L4/D1) may be between 0.6 and 1.6, preferably about 1.1. The second spacing D2 between the circulating radiation portion 110 and the second end 132 of the first additional radiation portion 130 may be greater than or equal to 0.2mm. The third distance D3 between the second ends 142 of the second additional radiation portions 140 and the circulating radiation portion 110 may be greater than or equal to 0.2mm. The above size ranges are found from a number of experimental results, which help to optimize the isotropy, the operating bandwidth (operational bandwidth), and the impedance matching (Impedance Matching) of the antenna structure 100.

Fig. 3 shows a schematic diagram of an antenna structure 300 according to an embodiment of the invention. Fig. 3 is similar to fig. 1. In the embodiment of fig. 3, the antenna structure 300 includes a circulating radiation portion 310, a balanced radiation portion 320, a first additional radiation portion 330, and a second additional radiation portion 340. In detail, the circulating radiation portion 310 has a first end 311 and a second end 312, and the circulating radiation portion 310 further includes an end widening portion (Terminal Widening Portion) 319 adjacent to the first end 311 thereof. The balanced radiating portion 320 includes a first branch portion 324, a second branch portion 325, and a connecting portion 326, wherein both the second branch portion 325 and the connecting portion 326 are widened (as compared to the embodiment of fig. 1). The addition of the widened portion allows tuning the impedance matching of the antenna structure 300 based on the actual measurement results. On the other hand, the first additional radiating portion 330 has a first end 331 and a second end 332, wherein the first additional radiating portion 330 further includes a first end bent portion (TerminalBending Portion) 334 adjacent to the second end 332 thereof, such that the first additional radiating portion 330 may substantially take on an inverted J-shape. Similarly, the second additional radiating portion 340 has a first end 341 and a second end 342, wherein the second additional radiating portion 340 further includes a second end bent portion 344 adjacent to the second end 342 thereof, such that the second additional radiating portion 340 may substantially exhibit a J-shape. The second end 332 of the first additional radiating portion 330 and the second end 342 of the second additional radiating portion 340 may extend in directions substantially approaching each other. According to the actual measurement result, the addition of the end bending portion not only increases the operation bandwidth of the antenna structure 300, but also reduces the overall size of the antenna structure 300. The remaining features of the antenna structure 300 of fig. 3 are similar to those of the antenna structure 100 of fig. 1, so that similar operation effects can be achieved in both embodiments.

Fig. 4 shows a schematic diagram of an antenna structure 400 according to an embodiment of the invention. Fig. 4 is similar to fig. 1. In the embodiment of fig. 4, the antenna structure 400 includes a circulating radiating portion 410, a balanced radiating portion 420, a first additional radiating portion 430, and a second additional radiating portion 440. It should be noted that the circulating radiation Portion 410 further includes a first Coupling Portion (Coupling Portion) 414 and a second Coupling Portion 415 separated from each other, wherein a Coupling Gap (Coupling Gap) GC1 is formed between the first Coupling Portion 414 and the second Coupling Portion 415. For example, the open end of the first coupling portion 414 may extend in the direction of the-Y axis, and the open end of the second coupling portion 415 may extend in the direction of the +y axis. The width of the coupling gap GC1 may be greater than or equal to 0.2mm. According to the actual measurement result, even if the circulating radiation portion 410 is designed to be partially discontinuous (having the coupling gap GC 1), it can provide an approximately isotropic radiation pattern. The remaining features of the antenna structure 400 of fig. 4 are similar to those of the antenna structure 100 of fig. 1, so that similar operation effects can be achieved in both embodiments.

Fig. 5 shows a schematic diagram of an antenna structure 500 according to an embodiment of the invention. Fig. 5 is similar to fig. 4, except that a first coupling portion 514 and a second coupling portion 515 of a circulating radiating portion 510 of the antenna structure 500 have different extension directions. For example, the open end of the first coupling portion 514 may extend in the +y direction, and the open end of the second coupling portion 515 may extend in the-Y direction. The remaining features of the antenna structure 500 of fig. 5 are similar to those of the antenna structure 400 of fig. 4, so that similar operation effects can be achieved in both embodiments.

Fig. 6 shows a schematic diagram of an antenna structure 600 according to an embodiment of the invention. Fig. 7 shows a schematic diagram of an antenna structure 700 according to an embodiment of the invention. Fig. 8 shows a schematic diagram of an antenna structure 800 according to an embodiment of the invention. According to the actual measurement result, if all or part of the radiation portions are widened, the impedance matching of the corresponding antenna structure can be finely tuned, and the approximately isotropic radiation pattern can be maintained. The remaining features of the antenna structures 600, 700, 800 of fig. 6, 7, 8 are similar to those of the antenna structures 100, 300 of fig. 1, 3, so that similar operation effects can be achieved in these embodiments.

Compared with the prior art, the novel antenna structure has the advantages of isotropy, small size, wide frequency band, planarization design and the like, so that the novel antenna structure is very suitable for being applied to various communication devices.

It should be noted that the device size, device shape, and frequency range are not limitations of the present invention. The antenna designer may adjust these settings according to different needs. The antenna structure of the present invention is not limited to the state illustrated in fig. 1 to 8. The present invention may include only any one or more features of any one or more of the embodiments of fig. 1-8. In other words, not all of the illustrated features need be implemented in the antenna structure of the present invention at the same time.

Ordinal numbers such as "first," "second," "third," and the like in the description and in the claims are used for distinguishing between two different elements having the same name and not necessarily for describing a sequential order.

While the invention has been described with reference to the preferred embodiments, it should be understood that the invention is not limited thereto, but rather, it should be apparent to one skilled in the art that various changes and modifications can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. An antenna structure, the antenna structure comprising:

a circulating radiation part, which is provided with a first feed-in point;

a balance radiation part having a second feed point and coupled to at least a first connection point on the circulation radiation part, wherein the balance radiation part is surrounded by the circulation radiation part;

a first additional radiating portion coupled to a second connection point on the circulating radiating portion; and

a second additional radiating portion coupled to a third connection point on the circulating radiating portion;

wherein the circulating radiation portion is disposed between the first additional radiation portion and the second additional radiation portion;

wherein a hollow portion is formed in the circulating radiation portion;

the circulating radiation part is provided with a first end and a second end, and the first feed-in point is positioned at the first end of the circulating radiation part;

the balanced radiating portion includes a first branch portion adjacent to or including a first end of the balanced radiating portion, a second branch portion adjacent to or including a second end of the balanced radiating portion, and a connection portion coupled between the first branch portion and the second branch portion.

2. The antenna structure of claim 1, wherein the antenna structure is capable of producing a radiation pattern that is approximately isotropic.

3. The antenna structure of claim 1, further comprising:

the medium substrate is provided with the circulating radiation part, the balance radiation part, the first additional radiation part and the second additional radiation part.

4. The antenna structure of claim 1, wherein the antenna structure covers an operating frequency band between 2400MHz and 2500 MHz.

5. The antenna structure of claim 1, wherein the circulating radiating portion has a hollow rectangular shape.

6. The antenna structure of claim 4, wherein the length of the circulating radiation portion is between 0.45 times and 0.85 times the wavelength of the operating band.

7. The antenna structure of claim 1, wherein the aspect ratio of the hollow portion of the circulating radiating portion is between 0.66 and 1.66.

8. The antenna structure of claim 1, wherein the circulating radiation portion further comprises a first coupling portion and a second coupling portion, and a coupling gap is formed between the first coupling portion and the second coupling portion.

9. The antenna structure of claim 1, wherein the balanced radiating portion has a U-shape.

10. The antenna structure of claim 1, wherein a slot is formed between the first branch portion and the second branch portion.

11. The antenna structure of claim 1, wherein the first branch portion of the balanced radiating portion is further coupled to the second end of the circulating radiating portion, and the second feed point is located at the second branch portion of the balanced radiating portion.

12. The antenna structure of claim 4, wherein the length of the balanced radiating portion is between 0.05 times and 0.45 times the wavelength of the operating band.

13. The antenna structure of claim 1, wherein the first additional radiating portion has an L-shape.

14. The antenna structure of claim 4, wherein the length of the first additional radiating portion is between 0.11 times and 0.31 times the wavelength of the operating band.

15. The antenna structure of claim 1, wherein the first additional radiating portion further comprises a first end bend portion.

16. The antenna structure of claim 1, wherein the second additional radiating portion exhibits an inverted L-shape.

17. The antenna structure of claim 4, wherein the length of the second additional radiating portion is between 0.11 times and 0.31 times the wavelength of the operating band.

18. The antenna structure of claim 1, wherein the second additional radiating portion further comprises a second end bend portion.

19. The antenna structure of claim 1, wherein the first additional radiating portion and the second additional radiating portion extend in the same or mutually adjacent directions.